The present invention relates to a heating apparatus such as a desk-top kitchen range, a gas cooker, etc. which prevents, during its use, entry of liquid, etc. spilt from an article to be heated, upon heating thereof.
Combustion apparatuses have recently undergone a marked development as is seen from progress of a method of supplying combustion air and fuel to a combustion portion and improvement of operational efficiency and operational feeling. Also in heating apparatuses, a method of supplying combustion air and fuel to a combustion portion has been changed from a Bunsen method to a forced premixed combustion method. Meanwhile, an arrangement of a combustion portion for securing excellent supply of combustion air thereto and improvement of operational efficiency and operational feeling from standpoint of consumers have been under study.
However, the forced premixed combustion method has such drawbacks that the heating apparatus as a whole is made complicated in structure, production cost of the heating apparatus rises due to the need for providing a fan for forcedly premixing combustion air and fuel and work for providing a power source for actuating the fan is required to be performed. Therefore, in heating apparatuses for home use, the Bunsen method is widely employed in which combustion air and fuel are mixed by action of self burning. However, in the Bunsen method, an air passage must be provided at each portion of the heating apparatus. Thus, the Bunsen method has such disadvantages that if liquid, etc. are spilt from an article to be heated, upon heating thereof, the liquid, etc. enter into the heating apparatus through the air passages, so that the interior of the heating apparatus is soiled by the liquid, etc. and service life of the heating apparatus lessens owing to rapid progress of corrosion caused by salt, water or the like contained in the liquid, etc.
Therefore, there is a demand for an inexpensive heating apparatus requiring no work at the time of its installation, which can be operated for a long time and satisfies the operator in operational efficiency and operational feeling.
Methods of supplying combustion air to a combustion portion of a heating apparatus can be roughly classified into three methods, namely the first method in which a entire amount of air neccessary for combustion is preliminarily mixed with fuel so as to be supplied to the combustion portion, a second method in which a portion of the air necessary for combustion is mixed with fuel so as to be supplied to the combustion portion and the remaining necessary amount of air is supplied from the periphery to the combustion portion by diffusion thereof at the time of combustion, and a third method in which the entire amount of air necessary for combustion is supplied to the combustion portion by diffusion. Here, the second method is described.
In the above described second method, an air passage must be provided at each portion of the combustion portion. The air passages can be provided in one of the following three arrangements. In the first arrangement of FIG. 1, air passages 4a and 4b are, respectively, disposed at a central portion and a peripheral portion of a burner 3 provided in a combustion portion 2 of a heating apparatus 1. In this first arrangement, if liquid is spilt from an article 5 to be heated, upon heating thereof, the liquid flows along a side surface or a bottom surface of the article 5 provided above the burner 3. Hence, the liquid flows into the air passages 4a and 4b provided at the central portion and the peripheral portion of the burner 3, respectively. As a result, the liquid soils the interior of the heating apparatus 1 or corrosion in the heating apparatus 1 progresses due to salt, water or the like contained in the liquid, thereby resulting in short service life of the heating apparatus 1.
In the second arrangement of FIG. 2, air in an amount necessary for combustion is obtained without providing the air passages 4a and 4b at the central portion and the peripheral portion of the burner 3, respectively. However, in this second arrangement, since no air passage is provided, a sufficient amount of air is not supplied to the burner 3, so that it is difficult to obtain proper combustion and thus, incomplete combustion is likely to take place. Meanwhile, in order to sufficiently perform supply of air through diffusion thereof, it is also possible to increase a distance between the article 5 and the burner 3. However, in this case, the combustion portion 2 becomes large in size and thus, the heating apparatus 1 as a whole also becomes large in size.
In the third arrangement of FIG. 3, an air passage 4 is provided at the central portion of the burner 3 without providing any air passage at the peripheral portion of the burner 3 and a cover member 6 which does not close the air passage 4 is provided above the air passage 4. The cover member 6 is so provided as to cover the air passage 4 when viewed from above. However, in this third arrangement, since the cover member 6 is provided separately from the burner 3, the operator may either lose the cover member 6 or fail to set the cover member 6 at the time of use of the heating apparatus 1, so that its originally planned effect cannot be achieved.